The present invention relates to a process for producing a semiconductor device. More particularly, the present invention is concerned with a process for producing a semiconductor device in which an appropriate amount of adhesive layer can easily be formed on the back of extremely thin chips to thereby enable avoiding chip breakage, chip cracking or package cracking, so that a productivity enhancement can be realized.
In recent years, the spread of IC cards has been promoted, and further reduction of the thickness there-of is now demanded. Accordingly, it is now required that the thickness of semiconductor chips, which has been about 350 xcexcm, be reduced to 50-100 xcexcm or less.
Thin semiconductor chips can be obtained by first adhering a surface protective tape for back grinding to a circuit surface of a wafer, subsequently grinding the wafer back and thereafter dicing the wafer. When the thickness of the wafer after the grinding is extremely small, chip breakage and chip cracking are likely to occur at the time of the dicing of the wafer.
As another means for attaining the reduction of the chip thickness, Japanese Patent Laid-open Publication No. 5(1993)-335411 discloses a process for producing semiconductor chips, in which grooves of given depth are formed from a wafer surface and thereafter the back of the wafer is ground. Further, this publication discloses a method in which, after the step of grinding the wafer back, pellets adhering to a mounting tape are detached from the mounting tape and fixed to a lead frame.
The chips obtained by this process are extremely thin and are likely to be broken in the subsequent mounting step.
When it is intended to pick up semiconductor chips adhered to a mounting tape and fix the picked semiconductor chips onto a substrate, it is common practice to employ the method known as the xe2x80x9cdispenser methodxe2x80x9d or the method in which a film adhesive is used.
In the dispenser method, a given amount of liquid adhesive is applied to sites of a substrate predetermined for fixing semiconductor chips with the use of a dispenser, followed by press-bonding/fixing of semiconductor chips thereonto. However, this disperser method has drawbacks in that controlling the discharge amount of adhesive is difficult to thereby cause the adhesive amount to fluctuate, bringing about a variation of quality, and in addition a bleeding phenomenon occurs because the adhesive is liquid. When bleeding of the adhesive occurs, the adhesive may curl up to the upper surface of the chips, or the semiconductor chips may be inclined, so that failure is likely to occur at the time of wire bonding. Moreover, when packages, after resin sealing, are placed in high-temperature conditions, package cracking may be caused by volatile components which evaporate from any bled adhesive.
In the method in which a film adhesive is used, a film adhesive cut into substantially the same shape as that of the chip is stuck to sites of a substrate predetermined for fixing semiconductor chips in advance, or a film adhesive cut into substantially the same shape as that of the chip is adhered to chips, and the chips are fixed through the film adhesive to the substrate. However, in this method, it is required to cut the film adhesive into substantially the same shape as that of the chip in advance, so that practicing the method is time-consuming. Further, the work for adhering the film adhesive of the same extremely small size as that of the chip is requisite, so that the method is very laborious.
Even if any of the above means is employed, minute chips which have been ground to an extremely small thickness to thereby become very brittle are handled, so that chip breakage is likely to result from slight misoperation.
Therefore, there is a demand for the development of a method of easily and securely forming an adhesive layer on, especially, the back of chips.
The present invention has been made in view of the above state of the prior art. In order to overcome the problems of the prior art, to overcome the problems of the prior art, the present invention to provides a process, for producing a semiconductor device in which an appropriate amount of adhesive layer can easily be formed on the back of extremely thin chips to thereby enable avoiding chip breakage, chip cracking or package cracking, so that a productivity enhancement can be realized.
The process for producing a semiconductor device according to the present invention comprises the steps of:
providing a wafer of given thickness having a surface furnished with semiconductor circuits and a back;
forming grooves of a cut depth smaller than the thickness of the wafer, the grooves extending from the wafer circuit surface;
sticking a surface protective sheet onto the wafer circuit surface;
grinding the back of the wafer so that the thickness of the wafer is reduced to thereby finally result in division of the wafer into individual chips with spaces therebetween;
sticking a dicing/die bond sheet onto the ground back of the wafer, the dicing/die bond sheet comprising a base and, superimposed thereon, an adhesive layer, the adhering performed so that the adhesive layer is brought into contact with the ground back of the wafer;
peeling the surface protective sheet from the wafer circuit surface to thereby cause the adhesive layer of the dicing/die bond sheet to be exposed through each space between neighboring individual chips;
cutting the exposed adhesive layer of the dicing/die bond sheet;
detaching the individual chips having the cut adhesive layer adhering thereto from the base of the dicing/die bond sheet; and
bonding the individual chips through the adhesive layer to a given substrate.
This process of the present invention enables efficiently performing the production of a device.